A Dallas police officer hugs a man following a prayer circle after a Black Lives Matter protest in Dallas on Sunday. (Carlo Allegri/Reuters)

A rare pause in political volleying prompted by a week of shocking killings gave way to familiar finger-pointing Sunday over who is to blame for the state of aggravated tensions between African Americans and law enforcement in the United States.

As Dallas reeled from the racially motivated targeting of police officers and protesters continued to march against police brutality in cities across the country, President Obama sought to allay fears that the country was falling into a state of discord and chaos and urged both sides to engage in respectful discourse.

“I would just say to everybody who’s concerned about the issue of police shootings or racial bias in the criminal justice system that maintaining a truthful and serious and respectful tone is going to help mobilize American society to bring about real change,” Obama said in Spain on Sunday during a European trip that has been overshadowed by a series of by crises on the home front. “It is in the interest of police officers that their communities trust them and that the kind of rancor and suspicion that exists right now is alleviated.

“So I’d like all sides to listen to each other,” he added.

The president plans to return home early, flying directly to a memorial service for the fallen officers in Dallas on Tuesday.

President Obama called for restraint and understanding as the country deals with the aftermath of police shootings that left black men dead in suburban St. Paul and Baton Rouge. Speaking to reporters in Madrid, Spain, Obama said anyone who attacks police officers is "hurting the cause." (Reuters)

Donald Trump, the presumptive Republican nominee, directed blame at Obama and the presumptive Democratic nominee, Hillary Clinton.

Citing the president’s claim on Saturday that the country is not as divided as some suggest, Trump countered that Obama is “living in a world of the make believe.”

“Look what is happening to our country under the WEAK leadership of Obama and people like Crooked Hillary Clinton,” Trump tweeted Sunday morning. “We are a divided nation!”

Five police officers were killed and seven were wounded Thursday night as they patrolled the streets during peaceful protests in Dallas by a young black man and an Army veteran who told police that he was angry about a spate of recent killings of black people by police and wanted to kill officers, especially if they were white.

As 25-year-old Micah Xavier Johnson targeted officers with a semi-automatic rifle, downtown Dallas transformed into a near war zone as police fell in the streets and dodged gunfire, and protestors who were caught in the crossfire bolted for safety.

Responding to the wave of demonstrations across the country that have been triggered by recent police shootings of black men, Former New York Mayor Rudy Giuliani said black parents should teach their children to be respectful to police. (Reuters)

The gunfire cut short the marching of hundreds of protesters who had taken to the streets that night in Dallas and elsewhere after two black men — Alton Sterling and Philando Castile — were killed during encounters with police in Louisiana and Minnesota, respectively.

It seemed, at first, that in a campaign cycle characterized by heated rhetoric and political tension, the tragic cascade of violent events compelled a rare pause in the rivalry between Trump and Clinton. Both Clinton and Trump cancelled most of their campaign activities on Friday and called for reflection and reconciliation.

But by Sunday, as the post-tragedy political thaw began in earnest, there was growing anxiety that the divisions that had led to days of protests and Thursday night’s brutal, retaliatory killings were an urgent problem.

Philadelphia’s former police commissioner, Charles Ramsey, warned on NBC’s “Meet the Press” that with the Democratic and Republican party conventions on the horizon, the tensions between police and the citizenry have created a dangerous situation.

“We are sitting on a powder keg,” Ramsey said. “Obviously, when you just look at what is going on, we’re in a very, very critical point in the history of this country.

“And I think you got two conventions coming up that are going to be very, very challenging to handle. And I don’t think they’re going to go without some incident taking place,” he added.

Former New York mayor Rudy Giuliani, a Republican, blamed Black Lives Matter protesters for the killing of police in Dallas, claiming that they sing “rap songs” that celebrate violence against police.

“When you say black lives matter, that’s inherently racist,” Giuliani said on CBS’s “Face the Nation.” “The police understand it and it puts a target on their back. Every cop in America will tell you that if you ask him.”

Asked whether Clinton and Trump would be capable and willing to stem the divides in a country seemingly riven by racial and political tensions, Sen. Cory Booker (D-N.J.) argued that Trump’s rhetoric had disqualified him for the task.

“We need people that bind our wounds and build bridges across our chasms,” Booker said on “Meet the Press.” “To see someone so callously stoking hate and fear, and inflaming divide, this is not person to be president of the United States I believe ever — but definitely not at a time we need a healer, a reconciler and somebody to remind us that as a nation our differences matter, but our country matters more.”

Presented with the same question, Sen. Bob Corker (R-Tenn.) argued that the rhetoric in politics contributed to the violence the country witnessed last week. But he added that he sees an effort within the Trump campaign to work to bring people together.

“I think there is going to be a sincere effort within the Trump campaign to do so,” Corker added.